The recent rapid advances in centrifugal technology for dewatering and thickening of wastewater sludges, against the background of rapidly increasing sludge disposal costs, are described. Examples are given of the key process design factors for wastewater sludge centrifuges, together with performance comparisons with conventional centrifuge technology. As a result of improved digestion, thickening of waste activated sludge can produce savings of 20-30% in the costs of disposal of dewatered digested sludge. Dewatering with advanced centrifuges is shown to have total operating costs for chemicals, personnel, power, capital servicing, transportation and landfill of the sludge at least 30% lower than with conventional technology. The replacement of dewatering equipment should be evaluated if the existing equipment is more than five years old, and the sludge is to be thermally processed or disposed of to landfill.